Telephone system



W. AITKEN.

v TELEPHONE SYSTEM. APPLICATION FILED MAR, 20. 1911.

$538,350. Patented Apr. 27,1920.

5 SHEETS-SHEET 1- I W. AITKEN.

TELEPHONE SYSTEM.

APPLICATION FILED MAR, 20' I917.

Patented Apr. 27, 1920.

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w I m is QN am H q bm- Am. rm. IP S RN .Q Q R6 Q6 R6 R6 m m w, 11 m s II} E Ifi KW .m W r 5 SHEETS-SHEET 3- 222253 wk E Patented Apr. 27, 1920.

W. AITKEN. TELEPHONE SYSTEM.

APRLICATION FILED MAR. 20. I917.

W. AITKEN.

TELEPHONE SYSTEM.

APPLICATION men MAR. 20. I917- I Patented Apr. 27, 1920.

5 SHEETS-SHEET 4f w. AITKEN. TELEPHONE SY STEM.

APPLICATION EILED MAR, 20, 19H.

1,338,350 Patented A r. 27,1920. 5 SHEETIS-SHEET 5v M MM multipled trunks which is the subject of my 1 Patent No. 1,311,432,

' as subscribers lines, with the STATES PATENT OFFICE- WILLIAM AITKEN, OF LONDON, ENGLAND, ASSIGNOE TO THE RELAY AUTOMATIC TELEPHONE COMPANY,

Improvement in Telephone Systems, of which the following is a specification.

A My. invention relates .toautomatic and semi-automatic telephone systems, and particularly to improvements in trunking systems to increase the efiiciencyof working between different switching stages in large systems, and'at the same time to reduce the cost particularly on systems using simple relays for switching and connecting.

The important features of my invention are 1. The provision of connecting means associated with each subscribers line, so that connection can be obtained with one of a plurality of different outgoing and incoming lines.

2. By the above means and the system of application Serial No. 156,069, July 29, 1919, the groups of lines, 'such' co-pendin ,ter-connecting of large and total outgoing trunk lines necessary for the trafli'c of the said large group of lines. 3. In known systems, the accessibility from and to adjacent lines is generally limited between 10 and 18, usually the former.

Y My system is only limited by the number of For example, if there trunks in a group.

to 59 can all be are 60 trunks, subscribers O 't'alkin simultaneously; H 500 trunks, then 500 a jacent -lines can be connected,

e. Following onthe above, the following facilities hitherto unnecessary ties are necessary to by the aid of suitable interm (a). No intermediate distributing facilib) Secondary pre-selectors are unneces sary, and the primary pre-selectors may be of smaller capacity;

5'. The number of trunk lines necessary to carry a given trafiic can be reduced (owto the large size the number of trunks can be increase without alteration in the-wiring of the switches.

6. Multipled trunks make itgpossxble now,

ing means described below, to 001111009} large total incoming rent when required. These relays ca connection between deemed essential are now ualize the traflic between the subscribers 'nes and the trunks,

' rupter,

of the, groups and iate connect- LIMITED, OFLONDON, ENGLAND."

1 Patented A a-.27, 1920.

group of lines, such as 1000 subscribers l1I1( 3S,t 0

the total incoming trunks necessary to carry the traffic of the group.

7. The incoming accessibility to 1000 subscribers introduces new methods of building up a connection, which with other new im- "provements are described later.

The invention covers particularly the effective use of the subscribers line switch in relationto outgoing and incoming trunk working, and the arrangement is therefore described in connection with three-digit calling, that is, having a capacity of 999 lines. The system may, however, be extended to any size by a corresponding use of imilar arrangements and apparatus, pr'eierahly with incoming trunks having access to outgoing trunks only.

'E'ach subscribers line is fitted with the usual line and cut-off relays, and in addition with a group of connecting rela s according to ,the trailiorequirements. ive will be suflicient for the average exchange. Preferably the connectingrelays have two armatures, one to be attracted by a current of a certain strength, and the other by a stronger current. "The former is preferably used for incoming calls and the latter "for outgoing calls, to allow of the registering meter be- I a further increase of curthe subscribers ing actuated by necessary'springs to connect a line to eith an incoming or an trunk as req ire'd.

The connecting relays are nation with auxiliary means used in combito bring about outgoin or incoming trunk. Such means, which 'etermine the idle line to be connected," are well known either utilizing re-'- .lays or in an electromechamcal form. In

one form of my invention I use a momentary circuit closing device which closes one at a time a plurality of circuits initially to energi'ze the connecting. means. ThlS interas it' may be called, may be continuor be controlled bythe energicallihg line relay in a well In another form ofmy inknown circuit determining arrangement described in- Bygraves specification SerialNo. 132884, Patent No. 1,269,903, June 18,1918.

At intermediate and final digit switchously driven, z'ation of the known manner. vention- I use the ing stages the two-armature lays are used outgoingacallingline and an idle its I in a somewhat diil'erent manner.

l 'the multipled intermediate lineson the subscribers line switches, for example, each relay can connect an intermediate line to one or other of two incoming trunks according as one or both armatures are attracted.

The intermediate lines are multipled over the incoming springs of the line switches according to my co-pending application, and at the other end terminate in the main circuit of a switch which may be of the electro-mechanical type. Preferably two-armature relays are associated with the intermediate lines, as many as may be necessary for the traflic between a group of in-. coming trunks and a group of subscribers, two lines bein connected by each relay. The number of intermediate lines equals the number of incoming trunks and the latter are multipled over all the switches of the intermediate lines, so that any intermediate line can connect with any incoming trunk.

. Each incoming trunk has associated with it a three-digit impulse responder, preferably individual to, the line. The responder is electro-mechanical, and a shaft rises and falls for"'each set of impulses, a different wiper, however, connecting in a different scribers line. switch;

. end being multipled at c over switches'd,

bank of contacts for each rise. hefirst rise connects up a relay controlling access to a particular group of 100 lines, the second rise controls access to a group of l0 lines, and the last connects with the particular subscriber called, to cause his line to connect with the calling incoming trunk over:

an intermediate line.

The outgoing lines are multipled over-the panying drawings in which v Figure 1 is a single line key or schematic dia am;

*- ig. 2 shows more particularly the sub- Fig. 3 shows the intermediate line connecting switch;'

Fig. 4' shows a method of opening the' common wiring connectionson a line switch.

Fig. 5 shows a relay line switch withthe circuit determining arrangement according to Bygraves Fig. 1 shows a subscribers line a having access to 5 outgoing. trunks b by a line switch 7, the outgoing trunks at their other associated with the intermediate lines 0 multipled over the incoming springs of the.

' subsc'ribers line switch f.

In 'Fig. 2theseries of relayscl to C5 constitutes the line switchf, the five outgoingjunctions QJl to 0J5 correspond to the outgoing trunks b and the.

011 the 13 to reduce current.-

. a ing. y mvention is illustrated by the accomv specification Patent .No.

1,269,903. Figs.- 6 and 7 show details.

junctions LI 1 to 1J5 correspond to the intermediate lines e. In Fig. 3 the series of relays (1 correspond to the switches 11 and the lines incoming at the top left hand corner correspond to the multiples a. In these figures also the double armatures are represented as secured together and capable of moving between two contacts, and it is to be supposed that when any relay is energized by' a weaker current the armature moves to ward it and when it is energized by the stronger current the armature moves away from it. The construction and mode of op- I eration of these C rela s are described below with reference to F igs. 6 and 7.

The circuits and operation of Fig.2 are as follows .O'ircuit 1.-Subscriber lifts receiver to call; line relay L energized.

Circuit 53.Momentary circuit completed over moving circuit closer CC; relay C5 energizes. (If OJ 5is engaged, C5 denergizes and C4 energizes, and so on, each connecting relay- C energizing in turn).

Circuit 3. 2 and 3).--Cut-ofl.' relay COR energizes in series with meter M and relay'R3 and second winding of C5 (meter does not energize).

Circa-it 4.COR and M are .now con-' off. R3 energizes and introduces resistance 13 can be short-circuited to cause meter to operate in well known manner. Another calling circuit being momentarily connected by the circuit closing device iii parallel with this nowengaged circuit will not be aifected, as COR having its windings inseries, is shunted by the en aged line low resistance cut-01f wind.-

he current will not be suflicient to energize COR,the C relay in series will not retain, and the interrupter will connect up the next C rela Circuit 5.- xtended line circuit in which R5 Fig. 3, ener es.

C'ircuit 6'. uarding relay R6 energizes. and connects battery in parallel by 3' to line 3.

The caller now sends impulses of threedigits, R5 denergizing for each openin of the circuit. R6 bein slow to release, oes not denerg'ize. In ig. 3, an electro-mechanical or stepping form of impulse responder, is shown, the shaft rising for each digit im ulse with the wipers or contact springs not making contact. After" a series of impulses, a ma et -WR presses a wiper W into contact wi a spring or plate S to completea momentary circuit, after which the shaft falls and rises again on the next series of impulses. The rela s RS1 etc.

connect the succeeding relays W in circuit.

.The wipersW are: for the sake of clearness shown diagrammatically to the left of the they are in reality carried by itas 1,.sae,aso.

shown in. the right bottom, corner of Fig. 2.

, cuit at the sub-station causes 'RS again,fand R7, R8 are agam .ener izes to press wiper Circuit 7.-The first openin of thev cir- 5 to denep. gize and R7 to ener ize.

Circuit 8.--Relay 8 then energizes. R7 and R8 are both slow to release.

' Circuit 9.R5 dener 'zing also energizes the lifting magnet L to lift the rack or shaft RS. one step, the release magnet Rel holdin 'lt; in that position between impulses. will assume that the rack has been lifted nine steps, and, in the interval between .the first and second digit, relay R5 is energized and R7 and then R8 denergi'ze. Circuit'10.-.-R7 completes a momentary circuit before R8 deener izes and W1 1 against contact 1.

Circuit 11.-R11 then energizes. R11 may be common to-a plurality of responders.

Circuit 1.Z.-Retaining circuit of R11;

Circuit 13.-Circuit completed by W'Rl to energize RS1.

Circuit Mir-Retaining circuit of RS1.

Circuit 15.-R8' denergizing completes a circuit to energize the release magnetwhen shaft 01' rack RS falls'to ndrmal position and opens the release circuit.

The impulses of the second digit lift shaft energized on the de-energization of R5.

Circuit 1 .-'-R7 deenergizing after the impulses extends circuit 10 'to the second wiper magnet WRQ to cause the wipers to make contact with S2 (assuming the second digit to be also 9 a Circuit 17.- ircuit 10, 16 is then extended so that R17 (Fig. 2) is energized.

Circuit 18."-Retaining circuit of R17.

Circuit 1.9.RS2 is ener 'zed-to extend the energizing circuit as be ore. 3

Circuit 20.Retaining circuit of RS2. R8 denergizing energizes Bel so that shaft again falls and Rel circuit is opened. On

' the third set ofimpulses R7 and R8 again energize andshaft BS is lifted. At the terof the series (9 again assumed).

mination 21-187 deenefgizes and circuit Circuit 10, 16 is extended to energize WR3 to cause I interrupter CO-rno the wipers to make contact. 3.

Circuit 522.The circuit is then extended to energize the called partys line relay L. Circuit 83.-Retaining circuit of-L. The

w energizes the relays C of the called' party one after the other through the resistance r7,?so that one armature only is attracted.

I will assume that the int-ermediateline connected to C2 is idle.

Circuit 25.-Third conductor circuit of} intermediate line completed through COR switches are shown, subscribers llne, each has also either a as for circuit 3.. R25 (Fi energizes.

COR energizing engages t e line as deenerglze to release the responder, and cuts circuit of the incoming trunk in off the parallel battery connection from circuit 3. 4

After conversation,- R5 deenergizes, then R6 so'that the guardin circuit is opened between the time R6 an R29 deenergize to release all relays in the circuit. If relay R28 had been energized over resistance r29, one armature only would have been attracted and a different trunk connected.

The circuit has been described in connection with the same subscribers line unit for} incoming and outgoing connections, forthe sake of sim lifying the drawing. It is of course to. e understood that two line switches are involved'in a connection. Circuit 5 is the outgoing trunk extending over the line switch to the calling line anfil incoming at the impulse relay. a

Circuit 30 is the talking circuit of the intermediate line which at one end is, multipled over a plurality of subscribers? line switches as describedin my co-pending ap-, plication, and at the other end terminates in a plurality of relays over'which the incoming trunks are multipled.

Fig. 4 shows a modification tojinsulate the circuits to the interrupter normally.

Circuit 31.A wire commonv to a group is connected to each line relay so that when a line relay is energized, a plurality of twoarmature relays is energized to pull up a light armature of each.

Circuit 32.Gircuits completed to the interrupter, the interrupter then pulling up plurality of lines .to relays C to earth (circuit '33) the calling line relays C only being energized." A

s In Fig. 5 two two-armature relay each associated with a switch consisting of Cc giving access to 5 outgoing and 5 incomi trunks. In addition, each subscribers line has the'usual line and cut-01f relays (L1 andCO respectively) Each line two-armature relay 'two single armature'relays S1, S2,/t0 switch into the circuit relays Cc, so that either one 5 relays l or both armatures are attracted to connect up either a plurality of incomingor outgoing trunk third-conductor circuits to the circuitdetermining relays CD to energize initially a particular: relay Cc on an idle trunk, as disclosed in Bygraves specification Serial No. 132884.

The circuits and operation of apparatus are as follows Circuit tL-Subscriberlifts receiver to call, relay L ener es.

Circuit 42.--Re ay S energizes to pull up tended third conductor circuit R03 with aretaining winding of C03 in series.

Circuit 4'7.-The subscribers line is thus extended to an outgoin trunk B03, A03. Relay L1 deenergizes, or S2 denergizes, and the initial energizing circuits are opened so that the line cannot be interfered with.

\ I Incoming calls.

Circuit 48.-The impulse responder; after receiving the trains of impulses, completes a circuit to energize relay S to pull up one armature, or energizes S in the case of line B.

Circuit 4.9.Battery is then connected through resistance r to the common side of the initial energizing windings of relays Cc.

Circuit 50.'-The third conductors of incoming trunks-T11 to T15 are extended to I. .the circuit-determining relays CD. If lines 1 to 5- are busy, CD5 will energize.

Circuitv 51.The initial energizing circuit of relay C05 to pull up one armature. The cut-off relay energizes and the wanted line is extended to the incoming trunk as before described.

The relays C maybe of the type shown in Figs. 6 and 7, consisting of a coil 63v surrounding aniron core '66. The magnetic return 64 is brought to the front to a point in line with the core and on this two armatures 65 and 67 are suspended. The armature 67 may be made lighter than 65 and placed nearer the core to render it more sensitive to weak currents. One group of springs 60, 61, 62,- is shown, but it will be readily understood that a plurality of groups may be similarly fitted. The armature 67 has an insulated stud 68 which forms a stop or rest for spring 60, and the ends of the U-shaped armature 65 are bridged by a strap 70 which carries an insulated stud 69 forming a stop or rest for the spring 61.

When a small current is passed through the coil 63, the armature 67 will be attracted to the core 66 and the spring 60 (which may be thinner than the other two) will be forced into contact with s ring 61. When a greater current is passe through coil 63 the armature 65 will also be attracted to the core 66 and spring61 will be lifted from spring 60 into contact with spring 62. In

the latter-condition both armatures are ope'rline with an idle line of one set and means for causing the relays to connect the line with an idle line of the other set.

2. In a telephone system, the combinat on of a line, a plurality of relays, each having two armatures, associated with said line, a set oflin'es connected to terminals of said relays, another set of lines connected, to other terminals of, said relays, means for causing one armature of a relay to be operated to connect the line with an idle line of one set and means for causing the'other armature to be operated to connect the line with an idle line of the other set. M i 3. In a telephone system the combination of a line, a plurality of relays, each having two. armatures, associated with said line, and a plurality of pairs of lines, one armature of each relay being adapted to connect the line to one of a pair and the other ar-.

mature adapted to connect the line other of the same pair. l

4. In a telephone. system, the combination of a line, a plurality of relays associated with the line, each relay having two armatures, a set of lines connected to terminals of said relays, a second set of lines connected to otherterminals of said relays, means for energizing the relays by a current to cause the armature of arelay to connect the line to an idle line of one set. and means for energizing the "relays by a to the stronger current to; cause the other armature of the relay to connect the line "to an idle line of the other set.

. momentarily one after the-other the-circuits tures, one adapted to connect the line to one line of a pair and the other ada ted to connect the line to the other line 0 the pair, a device adapted to close momentarily one after the other the circuits of the relays on one side, and a relay, associated with the line and adapted to close such circuits on the other side.

6. In a telephone system, the combination I of a line, a plurality of pairs of lines, a plurality of connecting relays each having two armatures, one adapted to connect the line to one line' of a pair and the other adapted to connect the line to the other line of the pair, a device adapted to close of the connecting relays on one side, a relay associated with the line and adapted to close such circuits on the other side, a cutoff relay and means whereby, when a connecting relay on an idle line is energized, a retaining circuit is established through the cut ofi relay.

7 In a telephone system, the combination of a. line, a plurality of .pairs of lines, a plurality of connecting relays each having two armatures, one adapted to connect the line'to one line of a pair and the other adapted to connect the line to the other line of the pair, a device adapted to close momentarily one after the other the circuits of the connecting relays on one side, a relay associated with the line and adapted to close such circuits on the other side, a cut-off relay and means whereby, when a connectin relay on a busy line is energized, the cut-o relay is prevented from energizmg and, on the device passing to the next connectin relay, the former connecting relay is cause to deenergize. I

v 8. In a telephone system, the combination of a line, a plurality of pairs of lines, a

plurality of relays each having two armatures, one adapted to connect the line to one line of a pair and the other adapted to connect the line to the other line of the pair,

a device adapted to close on one side an initial energizing circuit of the relay associated with an idle line and a relay asso-' ciated with the line and adapted to close such circuit on the other side.

9. In a telephone system, the combination of a line, aplurality of pairs of lines, a plurality of connecting relays each having two armatures, one adapted to connect the line to one line of a pair and the other adapted to connect the line to the other line of the pair, a device adapted to close momentarily one after the other the circuits of the connecting relays on one side, a relay associated with the line and adapted to close such circuits on the other side, a double wound cut-ofi' relay having its windings normally in series, means for energizing the cut-off relay and means for retaimng it throu h its two windings in parallel.

10. n a telephone system, the combination of a subscribers line comprising a third conductor, an incomin line, an outgoing line, a double wound re ay having two armatures, a resistance, means for passing a current through one winding of the relay so' as to cause one armature to connect the line with the outgoin line, means for inserting the resistance in the energizing circuit so as to cause the other armature to connect the line with the incoming line and means for connecting the other winding to the third conductor.

In testimony that I- claim the foregoing 

